A highly-rated French defender will officially complete a change to Emirates Stadium over the summer, but more developments are being called for.
David Luiz was acquired from London competitions Chelsea in 2019, while Pablo Mari was taken on a short term deal from Flamengo during the winter transfer window.
It could be that his loan deal is turned into a permanent agreement, with the Spaniard impressing before competitive football shut down amid the coronavirus pandemic.
Big things are also expected of Saliba, with the 19-year-old set to formally complete a switch from St Etienne at the end of the current campaign, having been permitted to invest 2019-20 on loan in his native France.
Campbell believes the talented youngster is going to be given a prominent role in Emirates Stadium, but Mikel Arteta has been urged to scour the market for additional defensive reinforcements.
The former Arsenal striker told the Chronicles of a Gooner podcast: “We made a very astute signing last year which many gave the club stick for Saliba.
“At least we’ve got a centre-half, a big, strong, fast, centre-half who’s going to go straight into that side. He has to.
“Do we need another one? Yes, we probably do. Can we get one? Who knows?
“If we could get Saliba in and bed him nicely then the defence is a lot younger and is a lot stronger.”
While the Gunners are being urged to further bolster their ranks on the area, the right option appears to have been found off it.
Arteta has provided cause for optimism through the opening months of his reign, with just two defeats suffered in 13 outings, and Campbell considers the former Arsenal captain will prove to be a success back in comfortable surroundings.
He added: “We have got the ideal manager but now we’ve got to find the right players in.
“I don’t think we’ve got the right balance of participant in our system to play the way Mikel Arteta wants. There’s lots of toing and froing of who knows what’s going to happen with this season?”
With Premier League football in lockdown, Arsenal sits ninth in the table, eight points adrift of the top four with 10 games due to be obtained in.